This invention relates to fumigants for stored agricultural commodities, and in particular to a fumigation method and applicator for prepackaged pesticides.
Pesticide treatment for stored fodder, grains, and the like is required to prevent infestation of the commodity. Depositories for such commodities, such as silos, elevators, flour mills, warehouses, feed mills, rail cars, barges, and ship holds, typically employ gas emitting pesticides which react with humidity to produce a toxic gas which permeates the stored commodity and completely fumigates same. These fumigants may include gas generating compounds, such as readily decomposable cyanides, alkaline earth phosphides or earth metal phosphides, which react with water vapor in the air contained within the grain depository to produce the toxic gas, which in the last recited examples are hydrogen cyanide, and hydrogen phosphide (phosphine) respectively. These fumigant gases are quite dangerous to humans, and the incomplete reaction of the pesticide with the water vapor leaves a residue of unreacted aluminum phosphide which remains toxic until the reaction is complete.
Certain types of commodities, such as wheat, may be fumigated by preparing the pesticide in a granulated or powdered form, and metering the pesticide directly into the grain as the same is being loaded into the storage depository. However, such a process is limited to special circumstances, and a pesticide residue remains in the wheat because the reaction with the water vapor is not always complete. In order to safeguard the ultimate consumer, regulations have recently been promulgated which require that the residue be is quite fine, the removal process is a very complicated and expensive procedure.
An alternate fumigation method includes the use of an aluminum phosphide chemical in powdered or pellet form, which is prepackaged in measured amounts into porous crepe paper bags or sachets, which when removed from their shipping container and exposed to atmospheric air, will liberate phosphine gas until exhausted or "gassed out". Heretofore, these sachets were manually inserted into the commodity in a uniform fashion after the depository was filled. The bags have been secured to one or more flexible lines by threading the same through an eyelet disposed in one end of the sachet, and tying the line thereto to facilitate removal of the sachets after fumigation. Not only is this method of application quite laborous and time consuming, but can also be quite dangerous, because it exposes the workers to the toxic fumigate gas for an unduly long period of time. The sachets begin to emit gas as soon as they are removed from the airtight shipping container and exposed to the atmosphere. Because the fumigate gases are quite toxic, it is essential that the workers vacate the fumigated areas very quickly before gas concentration levels developed to a hazardous or even lethal level. Hence, the time consuming manual application method used heretofore presents a substantial safety hazard to workmen performing the fumigation. Where very large amounts of grain are to be fumigated, such as in ship holds, a great many sachets must be distributed, therefore requiring a substantial amount of time, and exacerbating the safety hazard to the workmen. The longer the application requires, the longer the workmen are exposed to the hazards associated with the fumigation gas. Consequently, it is of the utmost importance that the application of the sachets to the commodity be performed not only in a uniform and careful manner, but also as quickly as possible.